Verbal particles are a closed class of uninflected words that co-occur with certain verbs. In some cases the verbal particles may have clearly distinguishable locative or directional meanings. In some languages some or all of the verbal particles also occur as (and are historically derived from) adpositions. In other languages, however, for example Ga'anda, the verbal particles are entirely distinct from adpositions. [Schachter 1985: 45-46]